These studies are concerned with genetically determined differences in adrenal corticosteroid and cholesterol ester metabolism in C57BL/10 and DBA/2 mice, and with gonadal effects on these areas of metabolism in these two strains. The principal aim of the project is to examine the relationship of polyunsaturated fatty acid metabolism, particularly the interconversion of adrenate and arachidonate, to the overall pattern of cholesterol ester composition in the two strains and in the different sexes of each strain. The relationship of these metabolic differences to the capacity of the adrenal to respond to ACTH by corticosterone production will be studied. In addition interstrain comparisons will be made of the detailed patterns of metabolism of steroids in the adrenals and of the efficiencies of the mechanisms for uptake of cholesterol from plasma into the adrenal glands.